This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. We are developing a mutant M1 muscarinic receptor that is trapped in the endoplasmic reticulum (ER) of cells. Addition of a pharmacological chaperone induces ER exit and stable expression of the fully functional receptor on the plasma membrane. We have made a GFP fusion protein of this mutant, and wish to explore its trafficking to the plasma membrane using TIRF in cells stably expressing this mutant. Ultimately, we wish to express this mutant receptor in primary cells and study its function and trafficking in a more natural context.